No mechanical fault was found with the aircraft. This analysis will focus on the operational, environmental, and human elements that were present. There is a history of DHC-6 operators successfully conducting take-offs from the marine dock after float-to-wheel conversions. Although this was the first attempt by this captain to take off from the dock, the first officer had completed a number of take-offs from the dock with another operator. Both pilots were highly experienced on type, and both mentally calculated that there was sufficient distance on the planned take-off path to get airborne safely. However, the take-off distance available measurement was shorter than estimated, and the reduction in take-off performance due to the effect of the dock depression was unforeseen. The combination of these circumstances resulted in the landing gear striking the wooden safety curb. The aircraft was being operated under CAR704 and the associated requirements of the COM. However, not all of these requirements were met in that the discussion between the captain and the DFO or chief pilot did not take place. This discussion might have led to an alternative course of action to mitigate the risks associated with taking off from the dock. The CVR had not operated during the accident flight due to a faulty inertial switch. In a more serious accident, crucial investigation data and safety information could have been lost. TSO C91-compliant Pointer ELT mounting brackets (part number2017) continue to fail, even in accidents where impact forces are relatively low. Although the ELT was inconsequential in this occurrence, its function in a more severe or remote accident could be critical to the survival of aircraft occupants. Failure of TSOC91-compliant Pointer ELT mounting brackets (part number2017) in a survivable accident could cause a malfunction of the transmitter and prevent a timely and effective search and rescue (SAR) response.Analysis No mechanical fault was found with the aircraft. This analysis will focus on the operational, environmental, and human elements that were present. There is a history of DHC-6 operators successfully conducting take-offs from the marine dock after float-to-wheel conversions. Although this was the first attempt by this captain to take off from the dock, the first officer had completed a number of take-offs from the dock with another operator. Both pilots were highly experienced on type, and both mentally calculated that there was sufficient distance on the planned take-off path to get airborne safely. However, the take-off distance available measurement was shorter than estimated, and the reduction in take-off performance due to the effect of the dock depression was unforeseen. The combination of these circumstances resulted in the landing gear striking the wooden safety curb. The aircraft was being operated under CAR704 and the associated requirements of the COM. However, not all of these requirements were met in that the discussion between the captain and the DFO or chief pilot did not take place. This discussion might have led to an alternative course of action to mitigate the risks associated with taking off from the dock. The CVR had not operated during the accident flight due to a faulty inertial switch. In a more serious accident, crucial investigation data and safety information could have been lost. TSO C91-compliant Pointer ELT mounting brackets (part number2017) continue to fail, even in accidents where impact forces are relatively low. Although the ELT was inconsequential in this occurrence, its function in a more severe or remote accident could be critical to the survival of aircraft occupants. Failure of TSOC91-compliant Pointer ELT mounting brackets (part number2017) in a survivable accident could cause a malfunction of the transmitter and prevent a timely and effective search and rescue (SAR) response. The take-off length available on the dock was shorter than estimated. This, in combination with the reduction in take-off performance due to the effect of the dock depression, resulted in the landing gear striking the wooden safety curb. The right main landing gear collapsed on landing as a result of damage incurred when the gear struck the wooden safety curb.Findings as to Causes and Contributing Factors The take-off length available on the dock was shorter than estimated. This, in combination with the reduction in take-off performance due to the effect of the dock depression, resulted in the landing gear striking the wooden safety curb. The right main landing gear collapsed on landing as a result of damage incurred when the gear struck the wooden safety curb. The company operations manual (COM) requirement for a discussion between the captain and the Director of Flight Operations (DFO) or chief pilot did not take place. This discussion might have led to an alternative course of action to mitigate the risks associated with taking off from the dock. The cockpit voice recorder (CVR) was not operating because of a faulty inertia switch. In a more serious accident, crucial investigation data and safety information could have been lost. Failure of Technical Standard Order (TSO) C91-compliant Pointer emergency locator transmitter (ELT) mounting brackets (part number2017) in an accident could cause a malfunction of the transmitter and prevent a timely and effective search and rescue response.Findings as to Risk The company operations manual (COM) requirement for a discussion between the captain and the Director of Flight Operations (DFO) or chief pilot did not take place. This discussion might have led to an alternative course of action to mitigate the risks associated with taking off from the dock. The cockpit voice recorder (CVR) was not operating because of a faulty inertia switch. In a more serious accident, crucial investigation data and safety information could have been lost. Failure of Technical Standard Order (TSO) C91-compliant Pointer emergency locator transmitter (ELT) mounting brackets (part number2017) in an accident could cause a malfunction of the transmitter and prevent a timely and effective search and rescue response. If the actual take-off distance available had been what was estimated by the captain (400feet), the take-off would likely have been successful.Other Finding If the actual take-off distance available had been what was estimated by the captain (400feet), the take-off would likely have been successful. On 13 July 2007, the TSB issued Safety Advisory A06A0114-D1-A1 (Emergency Locator Transmitter- Pointer Mounting Bracket P/N2017) to Transport Canada regarding the detachment of the emergency locator transmitter (ELT) from its mounting bracket. On 03 October 2007, Transport Canada responded to Safety Advisory A06A0114-D1-A1 and indicated that it would review the design approval to determine compliance with Technical Standard Order (TSO)C91. If required, the design standard of Airworthiness Manual551.104 will be reviewed and updated. The Department will also request a position from Pointer Sentry regarding this advisory. Pointer, as the manufacturer of the subject mounts, should take the lead on any required action concerning its design of the earlier TSOC91 mounting brackets. As a result of this accident, the operator has taken the following actions: ceased take-off operations from the dock; submitted a Service Difficulty Report on the faulty cockpit voice recorder (CVR) inertial switch to Transport Canada; and removed the clip-type ELT mounting bracket and replaced it with the mounting bracket with the hold-down strap.Safety Action Taken On 13 July 2007, the TSB issued Safety Advisory A06A0114-D1-A1 (Emergency Locator Transmitter- Pointer Mounting Bracket P/N2017) to Transport Canada regarding the detachment of the emergency locator transmitter (ELT) from its mounting bracket. On 03 October 2007, Transport Canada responded to Safety Advisory A06A0114-D1-A1 and indicated that it would review the design approval to determine compliance with Technical Standard Order (TSO)C91. If required, the design standard of Airworthiness Manual551.104 will be reviewed and updated. The Department will also request a position from Pointer Sentry regarding this advisory. Pointer, as the manufacturer of the subject mounts, should take the lead on any required action concerning its design of the earlier TSOC91 mounting brackets. As a result of this accident, the operator has taken the following actions: ceased take-off operations from the dock; submitted a Service Difficulty Report on the faulty cockpit voice recorder (CVR) inertial switch to Transport Canada; and removed the clip-type ELT mounting bracket and replaced it with the mounting bracket with the hold-down strap.